libmedia: use size_t consistently in rtm_pool.

* fixed a bad address error on x86_64.
ffmpeg: fix x86_64 build, remove libbz2

* AVCodecDecoder: for x86_64, use libswscale, asm is only for x86.
* CpuCapabilities: init capabilities to zero, fixes style.
* gfx_util.cpp: protect x86 specific code, fallback to C.
* x86_64: don't include unneeded x86 stuff.
* all arch: libbz2 is a build feature.
x86_64: publish some media libraries

* ffmpeg, libogg, libtheora, libvorbis, libvpx, speex